Alkylation of aromatic compounds

ABSTRACT

Alkylated benzenes such as ethylbenzene and cumene are produced by alkylation and/or transalkylation in the presence of an acidic mordenite zeolite catalyst having a silica/alumina molar ratio of at least 30:1 and a crystalline structure which is determined by X-ray diffraction to be a matrix of Cmcm symmetry having dispersed therein domains of Cmmm symmetry.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending applicationSer. No. 323,530, filed Mar. 14, 1989 now U.S. Pat. No. 5,004,841, whichis a continuation-in-part of application Ser. No. 123,741, filed Nov.23, 1987 now U.S. Pat. No. 4,891,448.

BACKGROUND OF THE INVENTION

This invention relates to the use of mordenite zeolites as catalysts inthe alkylation or transalkylation of aromatic compounds t producecumene, ethylbenzene and other alkylated benzenes.

Cumene, also known as isopropylbenzene, is useful for the production ofphenol, acetone and alphamethylstyrene. Ethylbenzene is useful in theproduction of styrene. Various processes for their manufacture areknown.

Various processing schemes comprising alkylation and/or transalkylationreactions are known to produce monoalkylaromatic products such as cumeneor ethylbenzene in high yields. However, existing processes are notwithout problems including the production of undesirable by-products.Examples of such by-products produced in conjunction with cumene includealkylating agent oligomers, heavy polyaromatic compounds and unwantedmonoalkylated and dialkylated compounds such as n-propylbenzene,butylbenzenes and ethylbenzene. The production of unwanted xylenes are aparticular problem in the production of ethylbenzene. Another problemwith existing processes concerns the use of Friedel Crafts catalystssuch as solid phosphoric acid or aluminum chloride. The phosphoric acidcatalysts generally require the use of a water co-feed which produces acorrosive sludge by-product. Problems concerning the sludge by-productcan be avoided by the use of zeolite catalysts.

It is known that aromatic hydrocarbons can be alkylated in the presenceof acid-treated zeolite. U.S. Pat. No. 4,393,262 (1983) teaches thatcumene is prepared by the alkylation of benzene with propylene in thepresence of a specified zeolite catalyst. U.S. Pat. No. 3,140,253,(1964) and U.S. Pat. No. 3,367,884 (1968) broadly teach the use ofacid-treated mordenite for the alkylation of aromatic compounds.However, such alkylations are generally not selective with respect tosite and number of substitutions. Further, catalysts are often quicklydeactivated requiring timely and costly replacements or reactivation.

Thus, there remains a need for an effective process for the preparationof alkylated benzenes having minimal levels of impurities utilizing acatalyst having low negative environmental impact and long life.

SUMMARY OF THE INVENTION

This invention is a process for alkylating benzene or substitutedbenzene to produce alkylated products having a low level of impurities.The invention is also directed to the transalkylation of polyalkylatedaromatics or transalkylation of a mixture of diisopropylbenzene andbenzene. The process comprises contacting the benzene with an alkylatingagent having from about two to about eighteen carbon atoms in thepresence of a catalyst under conditions such that alkylated benzenehaving a low content of impurities is produced. The catalyst exhibitslong life and is simply reactivated by a hot benzene flush whennecessary in the alkylation process. If required, reactivation may alsobe accomplished by a burn-off of carbonaceous deposits. The catalyst isan acidic mordenite zeolite having a silica/alumina molar ratio of atleast 30:1. In addition, the mordenite zeolite catalyst has acrystalline structure which is determined by X-ray diffraction to be amatrix of Cmcm symmetry having dispersed therein domains of Cmmmsymmetry.

Under the conditions of this process, cumene is produced having asurprisingly low bromine index and low levels of impurities such asn-propylbenzene, butylbenzene and ethylbenzenes. Ethylbenzene isproduced having low levels of impurities such as xylenes. Surprisingly,the catalyst does not readily deactivate.

Cumene produced by the practice of this invention is useful in theproduction of phenol. Ethylbenzene produced is useful in the productionof styrene.

DETAILED DESCRIPTION OF THE INVENTION

Any monocyclic aromatic compound may be alkylated or transalkylated bythe process of this invention. The aromatic compound is preferablybenzene or substituted benzene. Non-limiting examples of substitutedbenzenes which may be alkylated by the process of this invention includephenol and aniline. In the preparation of cumene and ethylbenzene, thearomatic compound is unsubstituted benzene or a mixture of benzene anddialkylated benzenes and other by-products produced in the alkylation ofbenzene with propylene or ethylene.

In a preferred embodiment, benzene is the aromatic compound which isalkylated using propylene as the alkylating agent to form cumene. In analternative preferred embodiment, a mixture of benzene anddiisopropylbenzene is transalkylated either in a separate reaction orconcurrently with the propylene alkylation. The diisopropylbenzenes maybe produced by the process of this invention or may be formed in adifferent alkylation process. In a third preferred embodiment, benzeneis alkylated with ethylene to form ethylbenzene.

The aromatic compound may be used neat in a liquid state, or dissolvedin a suitable solvent. Preferably, the aromatic compound is used in aneat liquid state. If a solvent is employed, any inert solvent whichsolubilizes the aromatic compound and does not hinder the alkylationreaction may be used. The preferred solvent is 1,3,5-triisopropylbenzeneor decalin.

In the alkylation of benzene to form ethylbenzene, the preferredalkylation agent is ethylene. In the alkylation of benzene to producecumene, the preferred alkylating agent is propylene. In anotherpreferred embodiment wherein cumene is produced by transalkylation, itis preferred that a mixture of the m-, o- and p-isomers ofdiisopropylbenzene and benzene are transalkylated. The isomers may beformed as by-products in the alkylation of benzene with propylene toproduce cumene either in the process of this invention or in acompletely different process. When the alkylating agent is the mixtureof isomers which ar formed as by-products in the alkylation of benzenewith propylene to produce cumene, the cumene may be distilled off orotherwise removed from the by-product mixture. The mixture is thenrecycled to be transalkylated in the same reactor where benzene isalkylated with propylene. Alternatively, cumene is formed by some otheralkylation process, such as a process using a solid phosphoric acidcatalyst, and the by-products are used as the transalkylating agent withbenzene is the process of this invention. Ethylbenzene may also byproduced by transalkylation.

In a particularly preferred embodiment for the production of cumene,benzene is alkylated by the process of this invention using propylene asthe alkylating agent. As discussed above, this process also producesdiisopropylbenzene as a by-product. The diisopropylbenzene produced inthe practice of this invention is a mixture of m-, o- and p-isomersenriched in the p-isomers. The cumene is separated from the by-productsby techniques known in the art such as distillation. The remainingmixture including the diisopropylbenzene is recycled for transalkylationwith benzene to form more cumene. The catalyst of this invention alsoshows reactant selectivity by transalkylating the para isomers at agreater rate than the ortho or meta isomers.

The catalyst useful in the practice of this invention is in acidicmordenite zeolite having a silica/alumina molar ratio of at least 30:1,a Symmetry Index (SI) as defined hereinafter of at least about 1.0, anda porosity such that the total pore volume is in the range from about0.18 cc/g to about 0.45 cc/g, and the ratio of the combined meso- andmacropore volume to the total pore volume is in the range from about0.25 to about 0.75. For the purposes of this invention, a micropore hasa radius in the range of about 3 angstrom units (Å) to 10 Å, a mesoporehas a radius in the range of 10 Å to 100 Å, and a macropore has a radiusin the range of 100 Åto 1000 Å.

The catalyst of the invention is an acid-modified zeolite withinterconnecting twelve-ring and eight-ring channels. Zeolites haveframework structures that are formally constructed from silicate andaluminate tetrahedra that share vertices. The tetrahedra may be linkedto form pores or channels. The size of the pores is determined by thenumber of tetrahedra in the ring. Twelve-ring zeolites contain ringsformed from twelve tetrahedra. Eight-ring zeolites contain rings formedfrom eight tetrahedra. The zeolites of this invention containinterconnecting twelve-ring and eight-ring channels. Examples of thezeolites suitable for use in this invention are mordenite, offretite andgmelinite. Mordenite-like zeolites, such as ECR-1 which is described inU.S. Pat. No. 4,657,748, and intergrowths of mordenite with otherzeolites are also suitable catalysts; as are zeolites having aone-dimensional pore system with twelve-ring channels, such as type L orrelated zeolites. Preferably the catalyst is an acidic mordenitezeolite.

The catalyst useful in this invention is prepared by a process whichcomprises contacting with strong acid an acidic mordenite zeolite havinga silica/alumina molar ratio less than 30:1 and a crystalline structurewhich is determined by X-ray diffraction to possess a Symmetry Index(SI) of from about 0.6 to about 1.0 under conditions sufficient toremove an amount of alumina sufficient to provide a silica/alumina molarratio of at least 30:1.

Mordenite is an aluminosilicate whose typical unit cell contents areassigned the formula Na₈ [(AlO₂)₈ (SiO₂)₄₀.24 H₂ O]. Mordenite is themost siliceous natural zeolite with a silicon/aluminum mole ratio(Si/Al) of about 5/1. The dimensions of the twelve-ring pores are about6.7×7.0 Å; the dimensions of the eight-ring pores are about 2.9×5.7 Å.The structure and properties of mordenite zeolite are described inZeolite Molecular Sieves, by Donald W. Breck (John Wiley & Sons, 1974),at pages 122-124 and 162-163, which is incorporated herein by reference.

The catalyst of this invention is prepared from a mordenite zeolitetypically containing cations of the alkali or alkaline earth metals, oralternatively ammonium ions. Preferably, the catalyst of the inventionis prepared from a sodium mordenite zeolite; even more preferably, froma sodium mordenite zeolite having a Symmetry Index less than about 1.0.The Symmetry Index is a dimensionless number obtained from the X-raydiffraction pattern of the sodium mordenite being measured in thehydrated form. Standard techniques are employed to obtain the X-raydata. The radiation is the Kα₁ line of copper, and a Philips Electronicsspectrometer is used. The mordenite zeolites exhibit an X-raydiffraction pattern whose diffraction peaks have d-spacingscorresponding to those of crystalline mordenites as reported by J. D.Sherman and J. M. Bennett in "Framework Structures Related to theZeolite Mordenite," Molecular Sieves; J. W. Meier and J. B.Uytterhoeven, eds., Advances in Chemistry Series, 121, 1973, pp. 52-65.The Symmetry Index is defined as the sum of the peak heights of the[111] (13.45, 2Θ) and [241] (23.17 2Θ) reflections divided by the peakheight of the [350] (26.25 2Θ) reflection. Preferably, the SymmetryIndex of the sodium mordenite ranges from about 0.50 to about 1.0. Morepreferably, the Symmetry Index of the sodium mordenite ranges from about0.60 to about 1.0.

Four ordered crystalline structures have been proposed to describe theX-ray diffraction data available for natural and synthetic mordenitezeolites. (J. D. Sherman and J. M. Bennett, op. cit., p. 53) Thesymmetries of these four structures are Cmcm, Cmmm, Imcm, and Immm asthese terms are defined by N. F. M. Henry and K. Lonsdale inInternational Tables for X-ray Crystallography, 3rd Ed., Volume 1,Kynoch Press (1969). X-ray diffraction data indicate that mordenites areeither physical admixtures or intergrowths of the Cmmm, Imcm, or Immmstructures with the Cmcm structure. Thus, mordenites can be generallydescribed as having a crystalline structure comprising a matrix of Cmcmsymmetry having dispersed therein domains of Cmmm, Imcm, or Immmsymmetry, or mixtures thereof. Preferably, the mordenite of thisinvention has a crystalline structure comprising a matrix of Cmcmsymmetry having dispersed therein domains of Cmmm symmetry. The SymmetryIndex is related to the symmetries of the crystals present in themordenite sample. A Symmetry Index in the range from about 0.60 to about1.0 provides the optimum sodium mordenite as starting material for theprocess of this invention.

The crystallite size of the original sodium mordenite may be any sizewhich yields a catalyst effective for the preparation of cumene having alow bromine index and low impurity levels. Typically, the crystallitesize may be in the range from about 500 Å to about 5000 Å. Preferably,the crystallite size is in the range from about 500 Å to about 2000 Å;more preferably, from about 800 Å to about 1500 Å. Generally, thecrystallites form aggregates which may be used as such or bound intolarger particles for the process of this invention. For example,extrudate can be made for a packed-bed reactor by compressing theaggregates into binderless particles of suitable sizes. Alternatively,the extrudate can be made via use of binders well-known to those in therat. The preferred particle size ranges from about 1 micron (μ) to about20μ.

The original sodium mordenite zeolite described hereinabove, or itsequivalent, is treated to obtain the catalyst of the invention for usein the alkylation process. The treatment involves contacting themordenite with acid. In one preferred embodiment, the treatment involvescontacting the mordenite with acid, calcining the acid-treatedmordenite, and further contacting the calcined mordenite with strongacid. In an alternative preferred embodiment, the catalyst is preparedwithout being calcined.

The initial acid treatment serves to remove most of the sodium ions, ortheir equivalents, from the original mordenite. The treatment may removea portion of the aluminum ions as well. Inorganic acids and organicacids are suitable compounds from which the hydrogen ions are obtainedfor the acid treatment. Examples of such acids are hydrochloric acid,hydrobromic acid, sulfuric acid, phosphoric acid, nitric acid, aceticacid, oxalic acid, and the like. Inorganic acids are the preferredsource of hydrogen ions; with hydrochloric, nitric and phosphoric acidsbeing more preferred and hydrochloric acid being most preferred. Anequally acceptable initial treatment involves ion exchange with ammoniumsalts, such as ammonium chloride. By this method the sodium ions, ortheir equivalents, are removed, but the aluminum ions are not displaced.On heating the ammonium exchanged mordenite, ammonia is given off andthe mordenite is converted to the acid form.

Typically, in the initial acid treatment the original sodium mordeniteis slurried with an aqueous solution of the acid. The acid solution mayhave any concentration, providing the catalyst obtained possesses theproperties and activity of the catalyst of this invention, these beingdescribed hereinafter. Preferably, the concentration of the aqueous acidsolution is in the range from about 0.01 N to about 6N; more preferablyin the range from about 0.5N to about 3.0N. The relative quantities ofaqueous acid solution to mordenite solid which are employed may vary.Typically, the ratio is less than about 15 cc acid solution per grammordenite solid. Preferably, the ratio is in the range from about 5 ccacid solution per gram mordenite solid to about 10 cc acid solution pergram mordenite solid. The temperature and the duration of the contact ofthe mordenite with the acid solution may also vary. Preferably, themordenite is contacted with the acid at a temperature in the range fromabout 10° C. to about 100° C. Generally, the contact time between theacid solution and the mordenite may vary from about 5 minutes to aboutseveral hours. It is important that there be sufficient time for theacid solution to contact all of the mordenite particles. Preferably, thecontact time is from about 5 minutes to about 60 minutes. The acidextraction, as described herein, may be repeated if desired. Afterwards,the mordenite is washed in water one or more times in order to rinseaway soluble species from the mordenite. Preferably, the water wash iscarried out at ambient temperature. Optionally, subsequent to the waterwash the mordenite is dried in air at a temperature in the range fromabout 20° C. to about 150° C.

In one treatment, following the exchange with acid and drying in air,the acidic mordenite zeolite is calcined in air or heated in an inertatmosphere, such as nitrogen. It is believed that this heat treatmentdislocated a portion of the aluminum from the zeolite framework;however, such a theory should not be taken as limiting of the scope ofthe invention. Typically, the temperature of the calcination or heatingmay range from about 250° C. to about 950° C. Preferably, thetemperature of the calcination or heating is in the range from about300° C. to about 800° C. More preferably, the temperature is in therange from about 400° C. to about 750° C. Most preferably, thetemperature is from about 500° C. to about 700° C.

After calcining the acid-treated mordenite described hereinabove, themordenite is subjected to an additional acid treatment for the purposeof further dealumination. The second acid treatment comprises contactingthe calcined mordenite with a strong acid under conditions sufficient toproduce the acidic mordenite catalyst of this invention. For thepurposes of this invention a "strong" acid is defined as an acid whichreacts essentially completely with the solvent to give the conjugateacid of the solvent. For example, if gaseous hydrogen chloride isdissolved in water, the acid-base reaction is complete to give theconjugate acid H₃ O+ and Cl-. Preferably, the strong acid is aninorganic acid. More preferably, the strong acid is nitric acid,hydrochloric acid, or sulfuric acid. Most preferably, the strong acid isnitric acid. The concentration of the strong acid will vary depending onthe acid selected. In general, the acid is employed in an aqueoussolution of any concentration which provides for the extraction ofaluminum from the calcined acidic mordenite, as described hereinafter.With nitric acid, for example, the concentration of the acid in theaqueous solution is preferably in the range from about 2N to about 15N.More preferably, the concentration of the acid is in the range fromabout 4N to about 12N. Most preferably, the concentration of the acid isin the range from about 6N to about 8N. The aqueous acid solution andthe calcined mordenite are contacted in any ratio that provides thecatalyst of the invention. Preferably, the ratio of aqueous acidsolution to mordenite is in the range from about 3 cc acid solution pergram mordenite to about 10 cc acid solution per gram mordenite. Morepreferably, the ratio is about 5 cc acid solution per gram mordenite.The temperature and the duration of the contact may vary depending onthe acid selected. Preferably, the mordenite is contacted with the acidsolution at a temperature in the range from about ambient temperaturetaken as 22° C. to about 220° C. More preferably, the mordenite and theacid are contacted at a temperature which allows for boiling of theaqueous acid under atmospheric conditions. Preferably, the duration ofthe contact is from about 1 hour to about 6 hours; more preferably, fromabout 1 hour to about 3 hours; most preferably, for about 2 hours. Whenthe contacting with strong acid is complete, the mordenite is filteredand washed repeatedly with water until the washings are acid-free.Preferably, the washed mordenite is heat treated and contacted withstrong acid more than once. Lastly, the washed acidic mordenite zeoliteis dried for several hours at a temperature in the range from about 100°C. to about 150° C. to remove physically adsorbed water. The driedacidic mordenite is activated by heating for about 2 hours at atemperature in the range from about 300° C. to about 700° C. Thisactivation may drive off more strongly bound water and any residualadsorbates.

In an alternative embodiment, the original sodium mordenite is treatedwith acid and retreated with strong acid without the intermediatecalcination step.

the catalysts useful in the process of this invention may also comprisea binder. Binders known to be useful with mordenite zeolite catalystsare useful for this purpose. Non-limiting examples of binders includealumina and silica with silica being preferred.

After the original sodium mordenite is treated with acid, optionallycalcined, and retreated with strong acid according to the process ofthis invention, an acidic mordenite catalyst is obtained which iscapable of converting benzene in a high conversion to cumene having alow bromine index and low levels of impurities or to ethylbenzene havinga low level of impurities. This catalyst exhibits specialcharacteristics by which it may be identified, specifically, thesilica/alumina molar ratio, and the Symmetry Index and porosity asdefined hereinafter.

An additional characteristic of the catalyst is its minimal deactivationin the alkylation of benzene or substituted benzenes. In the process ofthe present invention, the catalyst remains active for long periods ofuse. By remaining active, it is meant that the catalyst retains at leastabout 60, more preferably about 75 and most preferably about 90 percentof its activity for a period of at least about 500 hours of use, morepreferably for at least about 750 hours of use and most preferably forat least about 900 hours of use. The catalyst preferably remains activesignificantly longer than 900 hours of use.

In the alkylation reaction of the present invention, the catalyst,should it show any deactivation, may be regenerated by a benzene flushat a temperature of about 350° C.

As a result of the acid extractions, the silica/alumina molar ratio(SiO₂ /Al₂ O₃) of the acidic mordenite catalyst is increased over thatof the original sodium mordenite. Specifically, the acid-treatedmordenite catalyst has a silica/alumina molar ratio of at least 30:1.Preferably, the silica/alumina molar ratio ranges from about 40:1 toabout 300:1.

As a further result of the acid extractions and, optionally,calcination, the Symmetry Index of the mordenite catalyst is increasedover that of the original mordenite. The Symmetry Index is as definedhereinbefore. Since the Symmetry Index is derived from X-ray data, theIndex is related to the proportions of Cmcm, and Cmmm, Imcm, or Immmsymmetries present in the catalyst. The increase in the Symmetry Indexis indicative of the enrichment of the catalyst in the Cmcm component.For alkylations, a Symmetry Index of at least about 1 results incatalysts showing minimal deactivation that are capable of achievinghigh yields of alkylated benzenes. Preferably, the Symmetry Index rangesfrom about 1 to about 2.

A third property of the acid mordenite catalyst, by which it isidentified, is the porosity. All zeolites possess pores which form as anatural consequence of zeolite crystal growth. New pores ormodifications of existing pores can occur on treating the zeolites, forexample, with heat or acid as in the process of this invention.Typically, pores are classified into micropores, mesopores andmacropores. For the purposes of this invention a micropore is defined ashaving a radius in the range from about 3 Angstrom units (3 Å) to 10 Å.Likewise, a mesopore is defined as having a radius in the range from 10Å to 100 Å, while a macropore is defined as having a radius from 100 Åto1000 Å. After calcination and strong acid treatment, the acidicmordenite catalyst of this invention possesses micro-, meso- andmacropores. The porosity of the catalyst may be distinguished by thetotal pore volume defined as the sum of the volumes of the micro-,meso-, and the macropores per gram catalyst. A catalyst of thisinvention has a total pore volume sufficient to provide a high yield ofthe desired alkylated benzene with low levels of impurities. Preferably,the total pore volume is in the range from bout 0.18 cc/g to about 0.45cc/g. The porosity may be further distinguished by the relativedistribution of meso- and macropores, as found in the ratio of thecombined meso- and macropore volume to the total pre volume. A catalystof this invention has a ratio of combined meso- and macropore volume tototal pore volume sufficient to provide a high yield of the desiredalkylated aromatics with low levels of impurities. Preferably, the ratioof the combined meso- and macropore volume to total pore volume is inthe range from about 0.25 to about 0.75.

The measurement of the porosity, described hereinabove, is derived fromsurface area and pore volume measurements of mordenite powders obtainedon any suitable instrument, such as a Quantachrome Digisorb-6 unit,using nitrogen as the adsorbate at the boiling point of nitrogen, 77 K.The total pore volume (V_(T)) is derived from the amount of nitrogenadsorbed at a relative pressure close to unity. It is accepted that thisvolume constitutes pores of less than 1000 Å in radius. As statesearlier, for the purposes of this invention pores with radius of 10 Å orless are called micropores. Pores with radius from 10 Å to 100 Å arecalled mesopores, and pores with radius from 100 Å to 1000 Å are calledmacropores. Pores with radius in the 10 Å to 1000 Å range are known inthe literature as "transitional pores." The micropore volume (V_(m)) inthe presence of "transitional pores" is obtained by the t-method. Thedifference between the total pore volume and the micropore volume is thetransitional pore volume, (V_(t) =V_(T) -V_(m)). The cumulative poredistribution in the transitional pore range is used to calculate therelative volume contributions of mesopores and macropores. For example,the mesopore volume is calculated by multiplying the transitional porevolume by the fraction of the cumulative pore volume from 120 Å to 100Å, (V_(me) =V_(t) f_(me)). The macropore volume is then simply obtainedby subtracting the mesopore volume from the transitional volume, (V_(ma)=t_(t) -V_(me)). This approach ensures that the equation V_(T) =V_(m)+V_(me) +V_(ma) is satisfied. The adsorption isotherms obtained for themordenite catalysts of this invention are of Type I, which are describedby the Langmuir equation. The Langmuir surface area is obtained fromsuch equation. The methods used to obtain surface areas and pore volumesare described by S. Lowell in Introduction to Powder Surface Area (JohnWiley and Sons, 1979), or in the manuals provided with the Digisorb-6instrument made by the Quantachrome Corporation.

The acidic mordenite catalyst, identified hereinabove, is capable ofadsorbing biphenyl into the intracrystalline pore system, and converselydesorbing biphenyl. Biphenyl adsorption is effected by exposing theacidic mordenite to biphenyl vapors at 100° C. for a time sufficient toobtain near constant weight. Preferably, the adsorption capacity of theacidic mordenite for biphenyl is about 5 weight percent. Morepreferably, the capacity is about 10 weight percent. Biphenyl desorptionis effected by heating the mordenite-biphenyl sample in a dynamic heliumatmosphere from 25° C. to about 1000° C. at a heating rate of about 10°C./minute. The desorption of biphenyl may be followed experimentally bythermal gravimetric analysis combined with gas phase chromatography andmass spectrometry (TGA-GC-MS). It is found that weakly adsorbed biphenylproduces a weight loss at temperatures below about 300° C.; whereas,strongly adsorbed biphenyl produces a weight loss at temperatures fromabout 300° C. to as high as 1000° C. The amount of strongly adsorbedbiphenyl is estimated by subtracting the amount of weakly adsorbedbiphenyl from the total amount of biphenyl desorbed from the sample. Afully treated mordenite catalyst of this invention exhibits a sharpweight loss at temperatures below about 300° C. and little or no weightloss from 300° C. to 1000° C. In contrast, acid-exchanged mordeniteexhibits a sharp weight loss at temperatures below about 300° C., and asecond weight loss starting at about 300° C. and extending to 1000° C.It is believed that the weakly adsorbed biphenyl is located in sitesfrom which there is relatively easy exit; whereas the strongly adsorbedbiphenyl is located in sites from which there is relatively difficultexit. Thus, the acidic mordenite catalyst of this invention provideseasy access and egress to adsorbed biphenyl. Such a theory, however,should not be construed to be binding or limiting of the scope of theinvention.

The ratio of the benzene or substituted benzene to catalyst may be anyweight ratio which produces the desired alkylated benzene with arelatively high selectivity and a low level of impurities. Preferredratios will also be dependent on the reactor configuration. For example,in batch reactors, the weight ratio of benzene or substituted benzene tocatalyst is preferably in the range from about 0.1:1 to about 2000:1.More preferably, the weight ratio is in the range from about 10:1 toabout 500:1. Most preferably, the ratio is in the range from about 50:1to about 100:1. Below the preferred lower limit of 0.1:1, theproductivity will be very low. Above the preferred upper limit of2000:1, the conversion of the aromatic compound may be low.

The ratio of benzene or substituted benzene to alkylating agent may varydepending on the identity of the alkylating agent, type of reaction suchas batch or continuous and reaction conditions such as temperature,pressure and weight hourly space velocity (WHSV). When the alkylatingagent is propylene, the ratio of benzene to propylene is preferably fromabout 10:1 to about 3:1 in a continuous reactor. The preferred ratio maybe lower in a batch reactor with the propylene being supplied on demand.When diisopropylbenzene is used in a transalkylation reaction, the ratioof benzene to diisopropylbenzene is also preferably from about 10:1 toabout 3:1. When alkylation and transalkylation reactions are takingplace concurrently, the ratios of benzene to propylene anddiisopropylbenzene are about 10:1. Similarly, when the alkylating agentis ethylene, the ratio of benzene to ethylene is preferably from about10:1 to about 3:1 in a continuous reactor. As is recognized by oneskilled in the art, when different reactor configurations are used,different ratios of reactants may be preferred.

The alkylating agent may be introduced to the reaction all at once, asin the case of a liquid alkylating reagent. Alternatively, thealkylating agent may be introduced to the reaction on demand until thedesired degree of conversion is achieved, as in the case of a gaseousalkylating agent which is continuously fed into the reactor. When thealkylating/transalkylating agents are a mixture such as a mixtureincluding both propylene and diisopropylbenzene, the components may beadded independently.

The contacting of the benzene of substituted benzene with the alkylatingagent in the presence of the catalyst may occur in a reactor of anyconfiguration. Batch-type and continuous reactors, such as fixed bed,slurry bed, fluidized bed, catalytic distillation, or countercurrentreactors, are suitable configurations for the contact. Preferably, thereactor is fit with a means for observing and controlling thetemperature of the reaction, a means for observing and measuring thepressure of the reaction, and optionally a means for agitating thereactants. The benzene or substituted benzene may be in the molten,liquid form or in solution. The alkylating agent may be introduced inthe liquid or gaseous state, and may be added all at once at the startof the reaction, or fed continuously on demand from the reaction. Thecatalyst may be used in various forms, such as a fixed bed, moving bed,fluidized bed, in suspension in the liquid reaction mixture, or in areactive distillation column.

The contacting of the reactants in the presence of the catalyst mayoccur at any temperature or pressure which will produce alkylatedproducts having a low impurity content. In the production of cumene, thetemperature is preferably in the range from about 100° C. to about 250°C., more preferably about 130° C. to 200° C. In the production ofethylbenzene, the temperature is preferably in the range from about 100°C. to about 250° C., more preferably about 180° C. to 250° C., thepreferred lower limit of 100° C. the reaction proceeds slowly. Above thepreferred upper limit of 250° C., the impurity level increases.

The pressure in the reactor in batch reactions is preferably in therange from about 10 psig to about 200 psig. More preferably, thepressure is in the range from about 10 psig to about 100 psig. Below thepreferred lower limit of 10 psig, the alkylation rate is very low. Abovethe preferred upper limit of 200 psig the preferred propylene alkylatingagent will polymerize severely. Other reactor configurations will haveother preferred conditions.

The benzene, alkylating agent and/or transalkylating agent and catalystare contacted for a time sufficient to convert the benzene to alkylatedproducts, and sufficient to produce the desired yield of cumene.Generally, the contact time will depend on other reaction conditions,such as temperature, pressure and reagent/catalyst ratios. In theproduction of cumene in a typical stirred batch reactor with a benzene:catalyst ratio of about 50:1, at 150° C., a propylene pressure of about100 psig and a stirring rate of 2000 rpm, for example, the reaction timeis preferably in the range from about 0.1 hour to about 10 hours. Morepreferably, the reaction time is in the range from about 1 hour to about4 hours.

Following the alkylation/transalkylation of the benzene or substitutedbenzene, the product mixture may be separated by standard techniques.

For the purposes of this invention, the term "conversion" refers to themole percent of benzene or substituted benzene which reacts to formalkylated products. Typically, in the batch reaction to produce cumenefrom benzene and propylene, the conversion achieved in the practice ofthis invention is in the range of about 10 to about 40 mole percent.Below the 10 percent conversion, the cumene recovery is not practicaldue to the large benzene recycle. Above 40 percent conversion, theamount of by-products such as diisopropylbenzene is large resulting inthe need for a large transalkylation step.

Likewise, the term "benzene selectivity" refers to the mole percent ofreacted benzene which is converted to desired product such as cumene orethylbenzene. Smaller amounts of various by-products such as the o-, p-and m-isomers of diisopropylbenzene and other alkylated benzenes such asn-propylbenzene, butylbenzenes and xylenes are also formed. Typically,the benzene selectivity to cumene or ethylbenzene ranges from about 70mole percent to about 95 mole percent.

Another measure of selectivity is the "propylene selectivity" or"ethylene selectivity" which refers to the mole percent of propylene orethylene which is converted to cumene or ethylbenzene respectively.Preferably, the propylene selectivity or ethylene selectivity is atleast about 55 mole percent up to about 90 mole percent.

The concept of simultaneous high conversion and high selectivity todesired product may be expressed conveniently in terms of yield. For thepurposes of the present invention, the term "yield" refers to thenumerical product of conversion and selectivity. For example, a processto produce cumene according to the present invention operating at abenzene conversion of 15 percent, and a selectivity to cumene to 85percent, would have a yield of cumene of 12.75 percent, which is thenumerical product of 15 percent and 85 percent. Typically, the yield ofcumene or ethylbenzene achieved in the process of this invention, notconsidering any recycle or reactants, is at least about 10 mole percentand is preferably at least about 15 mole percent.

An additional factor that is important is the presence of variousimpurities in the product. Even very small amounts certain impuritiessuch as n-propylbenzene or propylene oligomers in the case of cumene, orxylenes in the case of ethylbenzene, create significant problems invarious application. Processes run under different conditions result indifferent levels of impurities. Thus, a particular advantage of theprocess of the present invention is the low impurity levels. In the caseof cumene production, low levels of oligomers as indicated by lowbromine index is also important. In cumene production, the bromine indexis preferably no greater than about 100, more preferably no greater thanabout 50 and most preferably no grater than about 20. Cumene produced bythe process of this invention preferably contains less than about 1000parts per million (ppm) impurities, more preferably less than about 200ppm. Ethylbenzene produced by the process of this invention preferablyhas less than about 1000 ppm xylene impurities, more preferably lessthan about 500 ppm.

An additional characteristic of the cumene produced by the process ofthis invention is the amount of color in the product. The cumeneproduced by the practice of this invention is essentially colorless.

SPECIFIC EMBODIMENTS

The following examples are given to illustrate the catalyst and theprocess of this invention and should not be construed as limiting itsscope. All percentages in the examples are mole percent unless otherwiseindicated.

EXAMPLE 1--CATALYST PREPARATION

Catalyst C-1, not an embodiment of the invention, is an H-mordenite witha Symmetry Index of 0.88 with a SiO₂ /Al₂ O₃ ratio of 15.2 and 20 weightpercent of a silica binder is used without further treatment. This istypical of commercially available mordenite. Its characteristics aregiven in Table I below.

Catalyst E-1, with a Symmetry Index of 2.1, is selected fromcommercially available hydrogen mordenites and used without furthertreatment and has the characteristics listed in Table I below. It alsocomprises 20 weight percent silica binder.

Catalyst E-2 is prepared by slurrying 300 g of Na-mordenite with a SiO₂/Al₂ O₃ ratio of 19 and a Symmetry Index of 1.26 with 3000 ml of a 1MHCl solution for 30 minutes at room temperature. The product is washedwith three 2000 ml portions of water and dried at 150° C. overnight. Thedry solid is stirred in 1500 ml of 6M HNO₃ and heated under reflux fortwo hours. The product is washed with two 2000 ml portions of water anddried at 150° C. in air overnight. The Symmetry Index is 1.68. Thecharacteristics of the catalyst are also listed in Table I below.

Catalyst E-3 is prepared from Na-mordenite with a SiO₂ /Al₂ O₃ ratio of15 and a Symmetry Index of 0.97 using the procedure described for E-3.The Symmetry Index is 1.38. The characteristics of the catalyst are alsolisted in Table I below.

Catalyst E-4 has a Symmetry Index of 1.85 and is selected fromcommercially available hydrogen mordenite and used without furthertreatment. It has the characteristics listed in Table I below. Thiscatalyst also includes 20 weight percent of a silica binder.

                                      TABLE I                                     __________________________________________________________________________         SiO.sub.2 /   Micro                                                                              Meso- Macro-                                                                             Total                                           Al.sub.2 O.sub.3                                                                   Si/Na    Pore Pore  pore Pore                                            (Molar                                                                             (Atomic                                                                            BET Volume                                                                             Volume                                                                              Volume                                                                             Volume                                     Catalyst                                                                           Ratio)                                                                             Ratio)                                                                             (m.sup.2 /g)                                                                      (ml/g)                                                                             (ml/g)                                                                              (ml/g)                                                                             (ml/g)                                     __________________________________________________________________________    C-1  15.2  96  389 0.190                                                                              0.023 0.036                                                                              0.244                                      E-1  38    466 489 0.180                                                                              0.080 0.034                                                                              0.294                                      E-2  84   1490 378 0.159                                                                              0.038 0.032                                                                              0.229                                      E-3  108  4200 418 0.173                                                                              0.083 0.062                                                                              0.318                                      E-4  156  4868 389 0.160                                                                              0.139 0.324                                                                              0.624                                      __________________________________________________________________________     Catalysts C-1 and E-4 are extrudates with a diameter of about 1.5 mm.     Catalysts E-1, E-2 and E-3 are crushed filtered particles of about 4 to 5     mm. Catalysts E-1 through E-4 are determined by X-ray diffraction to have     Cmcm symmetry having dispersed therein domains of Cmmm symmetry.

TRANSALKYLATION TO PRODUCE CUMENE

Reactant feed is a mixture of distilled heavies from a cumene productionand recycled benzene. The feed contains about 61 weight percent benzene;about 9 weight percent p-diisopropylbenzene (DIPB); about 8 weightpercent m-DIPB; about 6 weight percent cumene; about 4 weight percento-DIPB; about 3 percent 2-methyl, 2-phenylpentane; about 1 weightpercent 3-methyl, 3-phenylpentane and about 8 weight percent variousother impurities.

The pressure is 36 bar and the WHSV (feed weight hourly space velocity)is varied between about 0.4 and 0.8 hr⁻¹. Reactor effluent is cooled toroom temperature prior to analysis which is performed on line by gaschromatography.

EXAMPLE 2--Transalkylation Using Catalyst E-3

In this experiment, the molar ratio of benzene to diisopropylbenzene is5.9 and the WHSV is either 0.46 hr⁻¹ or 0.72 hr⁻¹ as shown in the tablesbelow. The temperature is varied and conversion and selectivity aremeasured at 140° C., 150° C. and 155° C. These results are shown inTable II below.

                  TABLE II                                                        ______________________________________                                        (CATALYST E-3)                                                                ______________________________________                                        Temperature (°C.)                                                                   150     150       140   175                                      Conversion (%)                                                                m-DIPB       59      70        27    75                                       o-DIPB       27      40        16    88                                       p-DIPB       82      86        68    88                                       Total        62      70        42    83                                       Selectivity (%)                                                               DIPB         92      91        92    87                                       Benzene      102     105       102   114                                      WHSV (hr.sup.-1)                                                                           0.72    0.46      0.46  0.46                                     Time (hrs)   90      60        170   100                                      ______________________________________                                    

The data in Table II demonstrates the long life of the catalyst used inthe process of the present invention. No deactivation is observed whenthe reaction is run for the cumulative time indicated under theconditions shown.

The amount of specified by-products and of cumene in the feed andeffluent are measured. These measured are done at a WHSV of 0.46 hr⁻¹.The results are shown in Table III below.

                  TABLE III                                                       ______________________________________                                        (CATALYST E-3)                                                                          Reactor                                                                              Reactor Effluent at                                                    Feed   140° C.                                                                          150° C.                                                                        175° C.                             ______________________________________                                        Ethylbenzene                                                                              170       50        80    646                                     (ppm)                                                                         n-propylbenzene                                                                           --        90       300   4722                                     (ppm)                                                                         t-butylbenzene                                                                            135      915       820    825                                     (ppm)                                                                         Cumene (wt %)                                                                              4        17        25    28                                      ______________________________________                                    

The data above indicates that impurity production increasessignificantly at higher temperatures.

Using the conditions described above, the transalkylation reaction usingCatalyst E-3 is run for a total of about 900 hours. No deactivation isshown over this time period.

EXAMPLE 3--TRANSALKYLATION USING CATALYST E-2

In this experiment, the molar ratio of benzene to diisopropylbenzene is5.9 and the WHSV is 0.72 hr⁻¹. The temperature is varied and conversionand selectivity are measured at 140° C., 150° C. and 160° C. Theseresults are shown in Table IV below.

                  TABLE IV                                                        ______________________________________                                        (CATALYST E-2)                                                                ______________________________________                                        Temperature (°C.)                                                                      140          150.sup.1                                                                              160                                     Conversion (%)                                                                m-DIPB          -5     33        26   63                                      o-DIPB           11    22        18   36                                      p-DIPB           54    70        68   84                                      Total            23    46        42   66                                      Selectivity (%)                                                               DIPB             95    95        95   93                                      Benzene          85    98        98   97                                      Time (hrs)      120    --        210  175                                     ______________________________________                                         .sup.1 Slight deactivation is observed at this temperature. The first         column represents results at the beginning of the reaction at this            temperature and the second column indicates results after 210 hours.     

The data in Table IV demonstrates the long life of this catalyst used inthe process of the present invention. Slight deactivation is shown at150° C. In this situation, the conversion of DIPB drops from 46 to 42percent. AT 140° C. and 160° C., no deactivation is observed.

The amount of specified by-products and of cumene in the feed andeffluent are measured. These measurements are done at a WHSV at 0.46hr⁻¹. The results are shown in Table V below.

                  TABLE V                                                         ______________________________________                                        (CATALYST E-2)                                                                           Reactor   Reactor Effluent at                                                 Feed      150° C.                                                                        160° C.                                   ______________________________________                                        Ethylbenzene  20          50     100                                          (ppm)                                                                         n-propylbenzene                                                                            <10         150     560                                          (ppm)                                                                         t-butylbenzene                                                                              130        840     790                                          (ppm)                                                                         s-butylbenzene                                                                              40         190     370                                          (ppm)                                                                         Cumene (wt %)                                                                              4.6         18.0    24.5                                         ______________________________________                                    

EXAMPLE 4--TRANSALKYLATION USING CATALYSTS E-1 and E-4

In this experiment, the molar ratio of benzene to diisopropylbenzene is5.8 and the WHSV is either 0.45 hr⁻¹ or 0.74 hr⁻¹. The temperature isvaried and conversion and selectivity are measured at 150° C. and 175°C. These results are shown in Table VI below.

                  TABLE VI                                                        ______________________________________                                        (CATALYSTS E-4 AND E-1)                                                       ______________________________________                                        Temperature (°C.)                                                                   150     150     150   150   175                                  Catalyst     E-4     E-4     E-1   E-1   E-4                                  Conversion (%)                                                                m-DIPB       <1      18      73    73    71                                   o-DIPB        5      14      43    69    66                                   p-DIPB       58      65      87    87    86                                   Total        25      37      73    78    76                                   Selectivity (%)                                                               DIPB         96      94      93    92    91                                   Benzene      95      99      110   120   110                                  WHSV (hr.sup.-1)                                                                           0.74    0.45    0.75  0.45  0.74                                 Time (hrs)   70      110     70    70    110                                  ______________________________________                                    

The data in Table VI demonstrates the long life of the catalysts used inthe process of the present invention.

The amount of specified by-products and of cumene in the feed andeffluent are measured. These measurements are done at a WHSV of 0.46hr⁻¹. The results are shown in Table VII below.

                  TABLE VII                                                       ______________________________________                                        (CATALYSTS E-4 AND E-1)                                                       Reactor      Reactor Effluent at                                              Feed         150° C.                                                                        150° C.                                                                        175° C.                                                                      150° C.                                                                      150° C.                       ______________________________________                                        Catalyst         E-4     E-4   E-4   E-1   E-1                                Ethyl-  <10      <10      90   150   140    230                               benzene                                                                       (ppm)                                                                         n-propyl-                                                                             <10       10     120   510   700   1210                               benzene                                                                       (ppm)                                                                         t-butyl-                                                                               200     1020    990   870   640    620                               benzene                                                                       (ppm)                                                                         s-butyl-                                                                              <10       100    140   500   410    560                               benzene                                                                       (ppm)                                                                         WHSV    --       0.74    0.45  0.74  0.75  0.45                               (hr.sup.-1)                                                                   Cumene  5.8      13.8    17.5  28.7  28.0  29.1                               (wt %)                                                                        ______________________________________                                    

EXAMPLE 5--BROMINE INDEX IN TRANSALKYLATION PRODUCT

Using Catalysts E-1 and E-4 and the procedure described above for thetransalkylation reaction, cumene is produced at the temperatures andWHSV shown in Table VIII. The bromine index of the cumene is measuredsing ASTM D-1492-7B. Results obtained are shown in Table VIII below.

                  TABLE VIII                                                      ______________________________________                                                                        Bromine                                                Temperature    WSHV    Index                                         Catalyst (°C.)   (hr.sup.-1)                                                                           (mg/100 g)                                    ______________________________________                                        E-1      130            0.78    3                                                      140            0.74    5                                                      150            0.75    2                                                      150            0.46    3                                                      160            0.73    3                                             E-4      150            0.76    2                                                      150            0.46    5                                                      175            0.75    12                                            ______________________________________                                    

COMPARATIVE EXAMPLE 1--TRANSALKYLATION USING CATALYST C-1 (NOT ANEMBODIMENT OF THE INVENTION)

Catalyst C-1 is tested using similar conditions and shows significantdeactivation after 110 hours of use. The percentage conversion of DIPBdrops from about 56 percent to about 15 percent in this time period. Thelevels of impurities produced at the highest activity are 320 ppmn-propylbenzene, 670 ppm t-butylbenzene and 290 ppm s-butylbenzene.

EXAMPLE 6--ALKYLATION OF BENZENE WITH PROPYLENE USING CATALYST E-4

A feed stream of benzene, propylene and propane is subjected toalkylation at various temperatures. The content of the feed stream isvaried. Feed Stream 1 91.4 weight percent benzene, 8.5 weight percentpropylene and 0.1 weight percent propane (5.8 molar ratio of benzene topropylene). Feed Stream 2 to 91.0 weight percent benzene, 8.9 weightpercent propylene and 0.1 weight percent propane (5.5 molar ratio ofbenzene to propylene). Feed Stream 3 is 87.4 weight percent benzene,12.4 weight percent propylene and 0.2 weight percent propane (3.8 molarratio of benzene to propylene). Feed Stream 4 is 93.4 weight percentbenzene, 6.5 weight percent propylene and 0.1 weight percent propane()7.7 molar ratio of benzene to propylene). The results are presented inTable IX below.

                                      TABLE IX                                    __________________________________________________________________________    (CATALYST E-4)                                                                         Propyl-                                                                  Benzene                                                                            ene  DIPB                                                                              m-DIPB                                                                             o-DIPB                                                                             p-DIPB  Reactant                                      Selec-                                                                             Selec-                                                                             Selec-                                                                            Selec-                                                                             Selec-                                                                             Selec-  Feed                                      Temp.                                                                             tivity                                                                             tivity                                                                             tivity                                                                            tivity                                                                             tivity                                                                             tivity                                                                             Time                                                                             Composi-                                  (°C.)                                                                      (%)  (%)  (%) (%)  (%)  (%)  (Hr)                                                                             tion                                      __________________________________________________________________________    130 71.1 54.6 28.5                                                                              4.9  --   23.6 22 1                                         145 74.0 59.2 25.0                                                                              9.9  --   15.1 22 1                                         155 78.8 65.6 20.1                                                                              12.2 --   7.9  24 1                                         165 86.4 73.6 13.7                                                                              9.3  --   4.4  30 1                                         175 91.6 83.4 7.9 5.3  --   2.6  80 1                                         185 94.8 88.0 5.1 3.3  --   1.7  48 2                                         175 91.1 83.0 8.6 5.7  --   2.9  24 3                                         175 94.7 87.0 5.1 3.4  --   1.7  45 4                                         __________________________________________________________________________

EXAMPLE 7--BROMINE INDEX IN ALKYLATION PRODUCT

Using Catalyst E-4 and the general process described in Example 6 above,the bromine index of the cumene produced at various temperatures andbenzene/propylene ratios is measured using ASTM D-1492-7B. The resultsobtained are shown in Table X below.

                  TABLE X                                                         ______________________________________                                        Temperature Benzene/Propylene                                                                           Bromine Index                                       (°C.)                                                                              Molar Ratio   (mg/100 g)                                          ______________________________________                                        145         5.8            2                                                  155         5.8           <4                                                  165         5.8           <1                                                  175         5.8           <1                                                  185         5.5           <1                                                  175         3.8           <1                                                  175         7.7           <1                                                  ______________________________________                                    

EXAMPLE 8--ALKYLATION OF PHENOL

A 100-g portion of phenol, 50 g of 1-octene and 100 g of1,3,5-triisopropylbenzene are reacted in the presence of a dealuminatedmordenite catalyst having a silica/alumina ratio of about 156. Thereactants are contacted at 200° C. for 2 hours at a starting pressure of38 psig. The product formed is colorless p-octylphenol. As determined bygas chromatography, the conversion of phenol is 40 percent, theconversion of octene is 80 percent and the p-octylphenol formed is atleast 98 percent pure.

EXAMPLE 9--PREPARATION OF ETHYLBENZENE

Using the general procedure described in Example 6, benzene is alkylatedwith ethylene to form ethylbenzene. The catalyst using has a SiO₂ /Al₂O₃ ratio of 44, the BET is 403 m² /g, the micropore volume is 0.137ml/g, the mesopore volume is 0.070 ml/g, the macropore volume is 0.040ml/g, the total pore volume is 0.237 ml/g and the Symmetry Index is1.52. The ratio of ethylene to benzene is 0.41. The temperature is 220°C. and the pressure is 36 bar. The yield of ethylbenzene is 32.9percent. The concentration of impurities are: toluene, 250 ppm; xylenes,60 ppm; cumene, 220 ppm; n-propylbenzene, 150 ppm; ethyltoluene, 140ppm; and butylbenzene, 200 ppm. No deactivation was observed after 140hours of operation.

What is claimed is:
 1. A process of alkylating benzene or substitutedbenzene, or transalkylating dialkylated benzene comprising contactingthe benzene or substituted benzene with an alkylating agent having fromtwo to eighteen carbon atoms in the presence of a catalyst, orcontacting the dialkylated benzene with benzene in the presence of thecatalyst, said catalyst consisting essentially of an acidic mordenitezeolite having a silica/alumina molar ratio of at least 30:1 and acrystalline structure which is determined by X-ray diffraction to be amatrix of Cmcm symmetry having dispersed therein domains of Cmmmsymmetry and having a Symmetry Index of at least about 1,the catalystbeing prepared by a method which comprises(A) calcining an acidicmordenite having a Symmetry Index between about 0.50 and about 1.0 andhaving a silica/alumina molar ratio less than 30:1 in air or heating theacidic mordenite in an inert atmosphere at a temperature in the rangefrom about 250° C. to about 950° C., and (B) contacting the calcined orheated acidic mordenite with strong acid to form an acidic mordenitehaving a silica/alumina molar ratio of at least 30:1 and having aSymmetry Index of at least about 1, and optionally (C) repeating Steps(A) and (B),under reaction conditions such that an alkylated benzene oralkylated substituted benzene is produced and the catalyst retains atleast about 60 percent of its activity for a period of at least about500 hours of use.
 2. The process of claim 1 wherein benzene is contactedwith an alkylating agent having two to twelve carbon atoms to produceessentially colorless alkylated benzene.
 3. The process of claim 2wherein the alkylating agent is propylene.
 4. The process of claim 2wherein the alkylating agent is ethylene.
 5. The process of claim 1wherein the catalyst has a silica/alumina molar ratio of at least about40:1 and no greater than about 300:1.
 6. The process of claim 1 whereinthe catalyst has a Symmetry Index of about 1 to about
 2. 7. The processof claim 1 wherein a temperature in the range from about 100° C. toabout 250° C. is maintained during the alkylation or transalkylation. 8.The process of claim 4 wherein a temperature in the range from about200° C. to about 250° C. is maintained during the alkylation oftransalkylation.
 9. The process of claim 1 wherein the benzene orsubstituted benzene is in a neat, liquid state and the alkylating agentis dissolved in the liquid state.
 10. The process of claim 1 wherein thebenzene or substituted benzene is dissolved in a solvent.
 11. Theprocess of claim 1 wherein substituted benzene is alkylated.
 12. Theprocess of claim 11 wherein the substituted benzene is phenol.
 13. Theprocess of claim 11 wherein the substituted benzene is aniline.
 14. Theprocess of claim 1 wherein in Step A the temperature is in the rangefrom about 300° C. to about 800° C., and wherein in Step B the strongacid is an inorganic acid in a second aqueous acid solution having aconcentration in the range from about 4N to about 12N, the ratio of thesecond aqueous acid solution to acidic mordenite is in the range fromabout 3 cc second aqueous acid solution per gram acidic mordenite toabout 10 cc second aqueous acid solution per gram acidic mordenite, thecontacting occurring at a temperature in the range from about 22° C. toabout 220° C.
 15. A process of producing an alkylated benzene comprisingcumene and ethylbenzene by transalkylation comprising contacting benzeneand a mixture of dialkylated benzenes in the presence of a catalyst,said catalyst consisting essentially of an acidic mordenite zeolitehaving a silica/alumina molar ratio of at least 30:1 and a crystallinestructure which is determined b y X-ray diffraction to be a matrix ofCmcm symmetry having dispersed therein domains of Cmmm symmetry andhaving a Symmetry Index of at least about 1,the catalyst being preparedby a method which comprises(A) calcining an acidic mordenite having aSymmetry Index between about 0.50 and about 1.0 and having asilica/alumina molar ratio less than 30:1 in air or heating the acidicmordenite in an inert atmosphere at a temperature in the range fromabout 250° C. to about 950° C., and (B) contacting the calcined orheated acidic mordenite with strong acid to form an acidic mordenitehaving a silica/alumina molar ratio of at least 30:1 and having aSymmetry Index of at least about 1, and optionally (C) repeating Steps(A) and (B),under reaction conditions such that an essentially colorlessalkylated benzene is produced and the catalyst retains at least about 60percent of its activity for a period of at least about 500 hours of use.16. The process of claim 15 wherein the catalyst has a silica/aluminamolar ratio of at least about 40:1 and no greater than about 300:1. 17.The process of claim 15 wherein the catalyst has a Symmetry Index ofabout 1 to about
 2. 18. The process of claim 15 wherein a temperature inthe range from about 100° C. to about 250° C. is maintained during thealkylation of transalkylation.
 19. The process of claim 4 wherein atemperature in the range from about 200° C. to about 250° C. ismaintained during the alkylation or transalkylation.
 20. The process ofclaim 15 wherein the aromatic compound is dissolved in a solvent. 21.The process of claim 15 wherein the dialkylated benzenes are produced bythe alkylation of benzene with an alkylating agent selected from thegroup consisting of ethylene and propylene in a process using a catalystcomprising an acidic mordenite zeolite having a silica/alumina ratio ofat least 30:1 and a crystalline structure which is determined by X-raydiffraction to be a matrix of Cmcm symmetry having dispersed thereindomains of Cmmm symmetry.
 22. The process of claim 15 wherein themixture of dialkylated benzenes is a mixture of the o-, m- and p-isomersof diisopropylbenzene produced by the alkylation of benzene withpropylene to produce cumene in a process using a solid phosphoric acidcatalyst.
 23. The process of claim 15 wherein the dialkylated benzenesare a mixture of the o-, m- and p-isomers of diisopropylbenzene and thepara isomer of the diisopropylbenzene reacts at a greater rate than theortho or meta isomer.
 24. The process of claim 15 wherein in Step A thetemperature is in the range from about 300° C. to about 800° C., andwherein in Step B the strong acid is an inorganic acid in a secondaqueous acid solution having a concentration in the range from about 4Nto about 12N, the ratio of the second aqueous acid solution to acidicmordenite is in the range from bout 3 cc second aqueous acid solutionper gram acidic mordenite to about 10 cc second aqueous acid solutionper gram acidic mordenite, the contacting occurring at a temperature inthe range from about 22° C. to about 220° C.
 25. A process of producingcumene by alkylation or transalkylation comprising contacting benzenewith propylene or diisopropylbenzene in the presence of a catalyst, saidcatalyst consisting essentially of an acidic mordenite zeolite having asilica/alumina molar ratio of at least 30:1 and a crystalline structurewhich is determined by X-ray diffraction to be a matrix of Cmcm symmetryhaving dispersed therein domains of Cmmm symmetry and having a SymmetryIndex of at least about 1,the catalyst being prepared by a method whichcomprises(A) calcining an acidic mordenite having a Symmetry Indexbetween about 0.50 and about 1.0 and having a silica/alumina molar ratioless than 30:1 in air or heating the acidic mordenite in an inertatmosphere at a temperature in the range from about 250° C. to about950° C., and (B) contacting the calcined or heated acidic mordenite withstrong acid to from an acidic mordenite having a silica/alumina molarratio of at least 30:1 and having a Symmetry Index of at least about 1,and optionally (C) repeating Steps (A) and (B),under reaction conditionssuch that essentially colorless cumene is produced and the catalystretains at least about 60 percent of its activity for a period of atleast about 500 hours of use.
 26. The process of claim 25 wherein inStep A the temperature is in the range from about 300° C. to about 800°C., and wherein in Step B the strong acid is an inorganic acid in asecond aqueous acid solution having a concentration in the range fromabout 4N to about 12N, the ratio of the second aqueous acid solution toacidic mordenite is in the range from about 3 cc second aqueous acidsolution per gram acidic mordenite to about 10 cc second aqueous acidsolution per gram acidic mordenite, the contacting occurring at atemperature in the range from about 22° C. to about 220° C.
 27. Theprocess of claim 25 wherein the catalyst has a silica/alumina molarratio of at least about 40:1 and no greater than about 300:1.
 28. Theprocess of claim 25 wherein the catalyst has a Symmetry Index of about 1to about
 2. 29. The process of claim 25 wherein a temperature in therange from about 100° C. to about 250° C. is maintained during thealkylation or transalkylation.
 30. The process of claim 25 wherein thebenzene is in a neat, liquid state and the diisopropylbenzene orpropylene is dissolved in the liquid state.
 31. The process of claim 25wherein the benzene is dissolved in a solvent.
 32. A process ofproducing ethylbenzene by alkylation or transalkylation comprisingcontacting benzene with ethylene or diethylbenzene in the presence of acatalyst, said catalyst consisting essentially of an acidic mordenitezeolite having a silica/alumina molar ratio of at least 30:1 and acrystalline structure which is determined by X-ray diffraction to be amatrix of Cmcm symmetry having dispersed therein domains of Cmmmsymmetry and having a Symmetry Index of at least about 1,the catalystbeing prepared by a method which comprises(A) calcining an acidicmordenite having a Symmetry Index between about 0.50 and about 1.0 andhaving a silica/alumina molar ratio less than 30:1 in the presence of anoxygen containing gas or heating the acidic mordenite in an inertatmosphere at a temperature in the range from about 250° C. to about950° C., and (B) contacting the calcined or heated acidic mordenite withstrong acid to form an acidic mordenite having a silica/alumina molarratio of at least 30:1 and having a Symmetry Index of at least about 1,and optionally (C) repeating Steps (A) and (B),under reaction conditionssuch that an essentially colorless ethylbenzene is produced and thecatalyst retains at least about 60 percent of its activity or a periodof at least about 500 hours of use.
 33. The process of claim 32 whereinin Step A the temperature is in the range from about 300° C. to about800° C. and wherein in Step B the strong acid is an inorganic acid in asecond aqueous acid solution having a concentration in the range fromabout 4N to about 12N, the ratio of the second aqueous acid solution toacidic mordenite is in the range from about 3 cc second aqueous acidsolution per gram acidic mordenite to about 10 cc second aqueous acidsolution per gram acidic mordenite, the contacting occurring at atemperature in the range from about 22° C. to about 220° C.
 34. Theprocess of claim 32 wherein the catalyst has a silica/alumina molarratio of at least about 40:1 and no greater than about 300:1.
 35. Theprocess of claim 32 wherein the catalyst has a Symmetry Index of about 1to about
 2. 36. The process of claim 32 wherein a temperature in therange from about 100° C. to about 250° C. is maintained during thealkylation or transalkylation.
 37. The process of claim 32 wherein thebenzene is in a neat, liquid state and the diethylbenzene or ethylene isdissolved in the liquid state.
 38. The process of claim 32 wherein thebenzene is dissolved in a solvent.